Method of producing beryllium-aluminium alloy



Patented July 25, 1933 UNITED STATES P ATENT OFFICE WALTER PFAU, 0F COLOGNE-MUHLHEIM, GERMANY, ASSIGNOR T0 EMIL BAG GLI, OF ZURICH, SWITZERLAND, AND EDWIN BURGER, 0F GISIKON NEAR ROOT, ,SWITZER- LAND METHOD OF PRODUCING BERYLLIUM-ALUMINIUM ALLOY 1N0 Drawing. Application filed March 5, 1932, Serial No. 597,089, and in Germany March 14, 1981.

This invention relates to a method of pro ducing beryllium-aluminium alloys.

Various methods of producing such alloys are known, one ofthem consisting in obtaining the beryllium and aluminium metals separately and then melting them together. However, owingto the high fusing temperatures required, heavy oxidation of the metals is unavoidable which renders the product useless. Another known process reduces the mixed metallic salts or oxides of beryllium and aluminium to a metal alloy in a thermochemical manner, but the alloys produced in this way are very impure and, furthermore,

do not ensue in compact form.

For technical purposes, electrolysis is therefore employed to produce berylliumaluminium alloys, and in this connection it has been proposed already to use as electrolyte a mixture of molten-double salts of these metals. The general practice has been in this respect to produce beryllium salt separately from aluminium salt inthe form of basic beryllium fluoride oroxyfluoride and to subject it in mixture with a suitable aluminium salt, such as the fluoride, to" electrolysis while adding alkaline and alkaline earth fluorides.

The prevailing practice carefully avoided to subject a basic fluoride or oxyfluoride to electrolysis, which contained aluminium besides beryllium, since it was generally assumed that a suitable electrolyte 'could be produced only from separately obtained basic beryllium fluoride or oxyfluoride.

According to the invention, berylliumaluminium alloys can be produced by simultaneously and jointly converting the metallic oxides of beryllium and aluminium contained intheberyl ores (beryl=3BeO.Al O .6SiO by suitable treatment, into basic fluorides or oxyfluorides and subjecting the salts thus gained, together with conducting salts, to

electrolysis of fused electrolytes, in which case, as manyexperiments have shown, a

beryllium-aluminium alloy will be precipitated on the cathode without trouble.

Compared with existing methods, the new process involves a considerable economic advantage in so far as the same operations or steps will instantly yield the'requisite double salts of beryllium and aluminium by the Simple application of hydrofluoric acid'."

Example 1 kilogram of beryllium ore is finely ground and then mixed with 1 kilogram of sodium fluosilicate whereupon the mixture is- To produce the heated for several hours. double basic fluorides the mixture is leached out with acidified water which will thencontain in dissolvedform the double fluorides of baryllium-sodium and aluminium-sodium.

The liquid is then decanted and treated with ammonia to precipitate the hydroxides of beryllium and aluminium which are separated by filtration and then treated with hydro; fluoric acid whereupon, after evaporation,

the basic fluorides or oxyfluorides of berylli- 11m and aluminium will jointly ensue in the proportion of 80% basic beryllium fluoride or oxyfluoride and 20% basic aluminium fluoride. In this composition'the metal contents amount to approximately 18% beryllium and approximately 6% aluminium, so

' the double basic fluorides or oxyfluorides of the composition described together with 1 kilogram of barium chloride. 1 Electrolysis is begun at a temperatureof approximately 1200 centigrade, the crucible being used as anode while a water-cooled iron pipe closed below and immersed in the melt serves pref erably as cathode. The electrolysis can be carried out at about 70 volts and a current in? tensity of 100 amperes corresponding to a current density of about 40 amperes per cm on the cathode, whereupon a beryllium-aluminium alloy will settle on the cathode in compact form or as coating. It is however more advantageous to operate with considerably higher current densities,'up to ten times the values given above, since during theevaporajointly obtained from the ores and adding thereto halogen salts of the alkaline and fialine earth metals to act as conducting 2; A method of producing beryllium-' aluminium alloys in compact form or as coating by electrolysis of fused electrolytes, which consists in employing as electrolyte a melt of basic oxyfluorides of beryllium and aluminium jointly obtained from the ores and adding thereto halogen salts of the alkaline and alkaline earth metals to act as conducting salts.

- WALTER PFAU. 

